Nickel base alloy



Patented Nov. 19, 1940 UNITED STATES PATENT OFFICE NICKEL BASE ALLOY Claude R. Bishop, Niagara Falls, N. Y., assignor to Haynes Stellite Company, a corporation of The invention relates to corrosion resistant alloys and particularly to nickel-base alloys having improved corrosion resistance.

Nickel-base alloys containing silicon, with or without additions of aluminum or copper or mixtures thereof are particularly resistant to many corrosive media, notably including hot aqueous solutions of hydrochloric acid. Alloys of the foregoing type are disclosed in Patents, 1,514,064

and 1,753,904, issued to A. J. Mandell and C. E. Plummer, respectively. While extensive use has been made of the excellent resistance of such alloys to corrosion by hydrochloric acid, there is a demand for alloys having even greater resistance 15 to this acid.

The principal object of this invention is to provide a nickel-base alloy having improved corrosion resistance, particularly to hydrochloric acid, and good physical properties. This and other ob- 20 jects are attained in the present invention by the application of my discovery that the addition of antimony, within certain definite composition limits, greatly improves the corrosion resistance and other properties of the nickel-base alloys.

Alloys included in the invention contain silicon in a proportion between 3% and 14%, preferably between 6% and 11%: antimony in a proportion between 0.02% and 10%, preferably between 0.3% and with or without aluminum 30 in a proportion between 0.02% and 5%, preferably between 0.5% and 3%; remainder nickel which may be replaced in part by cobalt or iron or both. In addition to the foregoing elements, a small proportion of manganese may be present 35 to improve the hot working characteristics of the alloy.

The following table indicates the composition of several representative alloys oi the invention and also indicates the results of corrosion tests made on samples of those alloys and on samples of alloys containing no antimony but otherwise similar to those of the invention.

The corrosion rates shown in the above table were determined by completely immersing the specimen in the acid solution indicated therein and maintaining that solution at constant temperature for the periods of time indicated. 5 The loss in weight was determined and reported as the number of milligrams dissolved per square centimeter of surface per hour 01 time.

The addition of 0.3% to 5% antimony to the alloys described herein, in accordance with the preferred procedure of the invention, does not materially afiect their mechanical propertiw, but greater proportions of antimony, that is, between 5% and 10%, usually lower the strength of the alloy somewhat. However, in both instances the 5 alloys possess excellent corrosion resistance, and

in apparatus constructed from alloys containing the greater proportions of antimony a proper allowance in the design of such apparatus may be made to compensate for the decrease in strength of the alloy.

1 claim:

1. An alloy comprising silicon in a proportion between 3% and 14%; aluminum in a proportion between 0.02% and 5%; antimony in a proportion, between 0.02% and 10%, serving to impart improved corrosion resistance to the alloy; the remainder nickel.

2. An alloy as defined in claim 1 in which the siilcon is in a proportion between 6% and 11%.

3. An alloy as defined in claim 1 in which the antimony is in a proportion between 0.3% and 4. An alloy comprising silicon in a proportion between 6% and 11%; aluminum in a proportion between 0.5% and 3%; antimony in a proportion,

between 0.3% and 5%, serving to impart improved corrosion resistance to the alloy; the remainder nickel.

' CLAUDE R. BISHOP. 

